In German Patent Specification No. 3336071, there is described an apparatus for opening and closing mold halves. In such apparatus the mold halves have rollers which travel in cam tracks of a sliding cam controller.
The vertical movement of the controller is directly used for opening the mold halves, that is to say, to produce rotational movement of the mold halves. Since the mold halves are relatively heavy, it is necessary for a considerable mass to be accelerated and retarded in a relatively short period of time. The high level of direct power transmission involved in such an arrangment gives rise to high wear phenomena and requires much external energy to be supplied.